1. Field of the Invention
This invention relates to a sintered ceramic product and to a method of making it. More particularly it relates to a sintered ceria/zirconia ceramic product.
2. Description of the Prior Art
Lange, F. F., J. Mat. Sci., 17(1982)255 proposed an yttria/ceria/tetragonal zirconia polycrystal ceramic on the basis of the phase diagram, which displayed a large tetragonal phase region up to almost 20 mole % ceria in the sintering range of zirconia-based materials (i.e. 400.degree.-1600.degree. C.).
Coyle, T. W. et al, Am. Ceram. Soc. Bull., 62(1983)966 manufactured material of the type proposed by Lange, and measured mechanical properties of such material containing 10-20 mole % ceria.
Tsukuma et al in U.S. Pat. No. 4,690,910 and J. Mat. Sci., 20(1985)1178 disclosed ceria/zirconia ceramics containing a minor proportion of from 4 to 30 mole % ceria, with lanthana, among other substances, mentioned as a possible impurity in the ceria, which was required to be at least 80 mole % pure. Preparation of the ceramics via a hydrolysis route was disclosed.
Tsukuma in Am. Ceram. Soc. Bull., 65(1986)1386 also disclosed ceria/zirconia ceramics containing from 8 to 16 mole % ceria and lanthana as an impurity (7 mole % of the commercial grade ceria used). The results of tests of mechanical properties were disclosed, together with a comparison thereof with yttria/zirconia ceramics.
Ceria/Zirconia ceramics are also disclosed in a review of tetragonal zirconia polycrystal in Int. J. High Technology Ceramics 3(1987)1; and Duh et al in High Tech. Ceramics (Elsevier Science Publishers H.V., Amsterdam (1987)1281) also disclosed ceria/zirconia ceramics, containing small quantities of rare earth metal oxides.